grep ^FAIL: build.log shows that most of the failures are C++-related; however, some of them are failed C and ObjC test cases too.
Having no PPC machine to test on, I'm not sure which to choose of the two solutions:
- disable clang on PPC
or
- just disable its test suite
Do the PPC maintainers have a preference? Thanks.

We're hoping to get a PPC machine for Fedora packagers exactly for this type of problems later this year. Until then I'd prefer to have the testsuite disabled. Disabling clang might cause lots of dependency errors in other packages.

Hm, you're right, flterm and pure have build dependencies on clang (I package the latter, and it probably should be fixed -- I tried switching to clang for building before and it didn't quite work out).
Do you need the test suite disabled on ppc64 as well? From the changelog it looks like you enabled them. I don't see a 'ppc64-koji' launcher so I can't test that build target.

Right, I noticed after sending my message that it's doing both builds. Still awaiting scratch build completion; if it's successful I'll commit and close this bug -- I'm assuming the PPC compose will rebuild any updated packages automatically?
It's probably too late to report this to upstream - they don't support older versions at all - but I'll make sure to try the first 3.0 pre-release on PPC as well and report the results before the final release goes out.

Wouldn't be it better to always run the test, but only don't fail the build on platforms where failuers are expected like on ppc or s390? E.g. use something like
make check \
%ifarch ppc s390
|| :
%else
%{nil}
%endif
s390(x) seems to have similar problems like ppc/ppc64. llvm-2.9-0.2.rc1.fc16 contains failed tests, but the build was successful, for llvm-2.9-2.fc16 the build fails because the failing tests.